Projection screen construction



F eb. 4, 1958 E- F. RUSCH PROJECTION SCREEN CONSTRUCTION Filed Feb. 17,1956 INVENTOR.

,EDWRD F. RUSCH BY United States Patent 2,821,883 PROJECTION SCREENCONSTRUCTION Edward F. Rusch, Cicero, ll|., assignor to Da-Lite ScreenCompany, Inc., Chicago, L, a corporation of Illinois ApplicationFebruary 17, 1956, Serial No. 566,167 1 Claim. (Cl. 88-2831) Thisinvention relates to projection screens of the type which, when not inuse, are stored up on a roller.

The screen, on which the images are cast from a projector, is usually asilver-coated vinyl-film composition, but several other silver-coatedscreen surfaces are also used. The spring loaded roller on which thisfilm sheet is wound, almost invariably, is made of wood. Notinfrequently the periphery of the roller is not too carefully machined.Accordingly, the surface of the roller may be a bit rough in spots, evenhave some ridges, bumps, or depressions. This vinyl-film composition,approximately .0l5" thick, is very pliable and impressionable. Were itwound directly onto the wood rollers, such a film would be impressedwith and have its otherwise very smooth surfaces distorted by the roughplaces on the roller. To obviate that possibility I underlay the screenfilm with a backing sheet.

Such backing sheet is formed of paper stock about half as thick as thevinyl-film, that is approximately .007". It is of a length such thatwhen wound around the roller it overlaps and extends a short distancebeyond the point of attachment of the inner edges of the film andbacking to the roller ledge.

If the comparatively abrupt termination of the free end of such backingsheet were used it would create a ridge longitudinally of the roller onwhich such a backing sheet and film screen are wound. In the course oftime, the pressure of the several convolutions of the film screen andthe tension caused by the usual spring loaded roller tends toaccommodate the successive layers of the pliable and impressionablematerial to the ridge-forming terminus of the backing sheet. As aconsequence a series of deformations would be formed transversely of thescreen. When the screen is unreeled for use these deformations tend toproduce annoying distortions of the image projected onto the screenalong such areas. When colored slides or film are projected on a screensurface it must be smooth and taut in order to present a clearundistorted picture.

The main object of this invention, therefore, is to provide an improvedform of backing sheet for a roll-up projection screen which willeliminate all possibility of the deformation of a viewing surface of thescreen, particula'rly a vinyl-film screen surface which is silvercoated; and to provide a constant smooth surfaced projection screenwhere the screen is of the roll-up type.

One embodiment of this invention is shown in the ac companying drawings,in which:

Fig. 1 is an enlarged, perspective view of a section of a wood roller,such as is generally used for coiling up projection screens, the viewshowing the ledge that is formed longitudinally thereto to provide forthe recessed attachment of the inner ends of the screen and its backingsheet;

Fig. 2 is an enlarged, transverse section of a screen roller showing theends of the screen and backing sheet stapled to the roller along therecessed ledge;

Patented Feb. 4, 1958 Fig. 3 is a further enlarged, perspective of afragment of an improved form of backing sheet constructed in accordancewith this invention; and

Fig. 4 is an enlarged, transverse, sectional view of a roller withseveral convolutions of the screen thereon;

Fig. 5 is a magnified fragment of Fig. 4 illustrating how the taperededge of the backing sheet, constructed in accordance with thisinvention, eliminates the abrupt ridge or detormation at the end of thebacking sheet.

The essential concept of this invention involves so forming a taperalong the free edge of a backing sheet as to present a very gradualreduction in the thickness of the overlapping portions of the backingsheet ad acently beyond the point of attachment of the screen andhacking sheet to the roller, thereby ellminaung the ridge which hasheretorore been formed by the conventional squareended backing sheet.

A pro ection screen assembly embodying the foregoing concept comprises aroller'1 wnereon is wound the silvercoated Vlflyl. [11111 0' and which18 undertaid with a hackmg sheet 9.

bflalatilel'lstlc with the conventional projection screen assembly, therouer '7 is mane or wood. Lougliudinany the peri hery is recessed tororm a ledge 10 wnereto the overlapping ends of the hacking sheet 9 andme screen mm 8 are attached by suitable fasteners 11, as, tor example,staples.

A1LLIUU511 not here shown, one end of the roller 7 is hUtlUwc:u uul. toprovide tor the housing or a torsion s ring, or the Lulu convention-anyused on window-shade rollers. LDC ends or the roller 7 mount theconventional natures (not here shown wncreoy the rouer is sus ended[[0111 UR: CUIlVtitlLlULlal Df'ctUAClS SCCUl'CO [O a SulLaDtC SUP-porung name, also not here shown. nee tor CXaHlple rateut mo. 239L686issued April 8, 1992 to Du Mats Ct at.

ror projection equipment of this kind, the screen 8 gencrahy is a veryimpressionable and pnaote vinyl nun. une lace l5 snvereu LLl the usualmanner.

the caching sheet 9, th accordance with this inventron, is Loruleu witha taper .12 or considerable width inwaruiy [I'Olll the tree edge or theDacnlng sheet 9. One or the most practical ways of achieving this Kindor a taper ts to "Salve" the paper by running along, what is to ac thetree edge or the Ddtit'ullg sheet when placed on me roller 7, anappropriately-written and dis osed Sanuutg urum. ny SUULl ct 1.1164135[DC Sufl'ZiCfi Of [116 Papet is cut away gradually LU a learner edge IOIabout three-quarters or an inch or an inch inwardly from the tree edge.

AS mg. 3 so clearly illustrates, the use of such a featheredgetl cachingsnect, when wound around the roller, terminates so gradually that itprecludes the formation of any MUG. or a ridge at the terminus or thatpart or the caching sheet that overlaps the initial Convolution, whichCLlaf'dCtdl'lZGS the conventional pro ection screen. 'lhere being noridge at the terminus or the overlapping convolutron of the backingsheet, the several convorunons of the screen 8 cannot be distorted alongthe overiap or the bdCAlng sheet. Consequently, there will be no creasesor other deformations appearing ll]. the screen when it is unreeled torpro ecuhg images thereon.

Uenerahy, the Wlfllll or the backing sheet is equal to the circumrercnceor the l'OllCl. plLtS approximately 20% additional I01 overlap, or whichlatter amount substanmany 73% is tapered or skived from the fullthickness of the sheet to a leather edge.

Although but one specific embodiment of this invention is herein shownand described it is to be understood that numerous details may bealtered or omitted without 3. departing from the spirit of thisinvention as defined by the following claim.

I claim:

A projection screen comprising, a roller peripherally recessed to form aflat ledge inwardly terminating at a normally-disposedlongitudinally-extending radial ridge and outwardly merging with theroller periphery circumferentially of the ridge, and a superimposedsilver screen and backing sheet of a combined thickness equal to theradial dimension of the ridge and secured to the ledge with the ends ofthe screen and sheet abutting the ridge, the backing sheet being of awidth not less than the circumference of the roller and formed with along-angled taper for a material distance inwardly from its free edge.

References Cited in the file of this patent UNITED STATES PATENTSEdmiston Oct. 17, 1899 Weston Aug. 19, 1902 Gamrneter Sept. 19, 1911Finstone Mar. 16, 1926 Heck July 11, 1933 Rice Aug. 22, 1933 Gramp Aug.2, 1955 FOREIGN PATENTS Great Britain Oct. 25, 1950

